A fatberg which was discovered beneath the street of London recently is reported to be the size of a Boeing 747 and took Thames Water over a week to remove.

So what is a fatberg? Basically, fatbergs are comprised mainly of cooking oil, wet wipes, and general household waste that people put down the sink. When hot cooking oil is poured down the drain and it hits the cold water in the sewer, it congeals into a large fatty mass which needs to be removed.

Thames Water said in a press release that the fatberg formed a 262-foot blob beneath the Shepherd’s Bush Road and a team of experts took a week, working day and night, to remove the blockage. The fatberg needed to be broken up to prevent the sewer from flooding into nearby homes and businesses.

Business Insider reported today that the press release moaned to residents about the need for them to be more careful about what they put down their kitchen sinks and toilets. Their laziness has caused the company a lot of work and extra expense, which will most likely be reflected in forthcoming water bills.

Thames Water noted that, even though the Shepherd’s Bush fatberg wasn’t as bad as a 15-tonne fatberg in Kingston last year, it was still a pain in the backside for the company.

Dave Dennis, the Thames Water sewer operations manager, said on the company’s website:

“We have 108,000km of sewers, and that’s a lot of pipe to keep clear. We spend £12 million a year tackling blockages, most of them formed because people have tipped cooking fats down the drain and wet wipes down the loo. The sewers serve an important purpose – they are not an abyss for household rubbish. Fat goes down the drain easily enough, but when it hits the cold sewers, it hardens into disgusting ‘fatbergs’ that block pipes.”

Thames Water already spends around $20 million annually in the war against fatbergs, with the worst area in London for them being Harrow, which has had an estimated 13,417 fatbergs in the last five years.